Dental Unit water system (DUWS) Waterlines (DUWL): DCUs contain elaborate systems of interconnected plastic tubing, to provide cooling systems to dental high-speed hand-pieces and burs and to prophylactic hand-pieces. These DUWL have been shown to develop microbial biofilms overnight when the DCU is not in use. The primary organisms isolated from DUWL are Gram-negative bacteria that include Legionella, Pseudomonas, and Mycobacterium spp. And others are Micrococcus, Sphingomonas Spp. These organisms may be transferred directly to the patients and office personnel via droplet transmission and improper maintenance of the DCUs.
A recent report exists of a patient developing an acute infection following dental treatment that resulted from contaminated water lines. Disinfection of the DUWS must be performed.
The microbial quality standards for potable water vary across the world with the ADA specifying ≤200 cfu per millilitre of aerobic heterotrophic bacteria for DCU output water and the CDC recommending that the DCU output water should be ≤500 cfu per milliliter of aerobic heterotrophic bacteria.
In India, one should ensure that the water supplied to the DCU should be from a Class C source – “Drinking water source with conventional treatment followed by disinfection”. It has been shown that peroxide, phenol, chlorite and povidone-iodine based, and hydroxide containing products and electrochemical activated agents (ECA) for disinfection of DUWLs have been able to bring about ≥95% removal of the biofilm.